Various techniques have been proposed to reduce rotation loosening of a bolt with respect to a nut or the like.
For example, in order to increase a fixation strength and a friction strength on a thread surface, an adhesive agent or a locking agent is applied to the thread surface.
In addition, it is proposed that a projection of a special shape is provided on a threaded part such that the projection interferes with a internal thread so as to increase a friction on a thread surface.
Patent Document 1: JPH8-128420A (JP1996-128420A)
Patent Document 2: JPH10-331831A (JP1998-331831A)
Patent Document 3: JP2001-173627A (JP3871483B)